<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script>
    const list = [
      { 'id': '29', 'pid': '', 'name': '总裁办' },
      { 'id': '2c', 'pid': '', 'name': '财务部' },
      { 'id': '2d', 'pid': '2c', 'name': '财务核算部' },
      { 'id': '2f', 'pid': '2c', 'name': '薪资管理部' },
      { 'id': 'd2', 'pid': '', 'name': '技术部' },
      { 'id': 'd3', 'pid': 'd2', 'name': 'Java研发部' }
    ]

    const map = {}

    list.forEach(item => {
      item.children = []
      map[item.id] = item
    })

    console.log(map)
    console.log(list)

    const newList = []

    list.forEach(item => {
      // console.log(item)

      if (item.pid) {
        const par = map[item.pid]
        par.children.push(item)
        console.log(par)
      } else {
        newList.push(item)
      }
    })
    console.log(newList)

  </script>
</body>

</html>